According to Microsoft, MSN Juku is a "local innovation developed by MSN China...based on Windows Live Messenger networks."

At the time, local Chinese media were already commenting on the similarities in the look-and-feel between MSN Juku and Plurk, with one calling it a "bandit" version (Chinese slang for a knock-off).

That accusation was brought out into the open today by Plurk. In a blog post, the company said that while "imitation may be the sincerest form of flattery, but blatant theft of code, design, and UI elements is just not cool, especially when the infringing party is the biggest software company in the world."

Plurk showed purported screenshots of MSN China's new service, which it called "a little overly inspired" by Plurk's 18-month-old service. It also showed snippets of JavaScript and CSS code from both services, and claimed that 80% of the codebase "appears to be stolen directly from Plurk."

Plurk said the two services are so similar that some bloggers speculated that Microsoft's service might have been based on a partnership with Plurk, a rumor it quickly dismissed.

"We were never contacted by any party at M$ to collaborate on such a venture nor did we give any prior written or verbal permission to anyone on their side to take our code, take our CSS, and copy the essence and ethos of our service," wrote Plurk. "As a young startup, we're stunned, shocked, and unsure what to do next and need your support and suggestions."

Plurk has largely failed to make a dent in the English-speaking Web, where Twitter dominates. It had 766,000 visitors last month, compared to 1.3 million for Friendfeed and 131 million for Twitter, according to statistics from Compete.com.

Plurk is also banned in China, along with Twitter and some other social-networking services, by the government for political reasons.

However, Plurk reportedly tops the microblog market in Taiwan, ahead of Twitter. It is also popular in other Asian countries such as Indonesia and Singapore. One reason: Twitter, due to cost and time, only operates a fully localized service in Asia for Japanese users. Plurk, meanwhile, solicits help from volunteers in each country to help translate key commands and phrases, with the best chosen by a vote in that country. That allows Plurk to offer its service in 33 languages, including Chinese, Gaelic, Arabic and Japanese.